On vehicles where there is a single 4 pin extension cable these can be used to convert it into a Y-cable set for a twin lens camera. As the existing 4 pin cable may not have been designed to carry 2 video signals there is always a possibility you will get a small amount of cross-channel interference (ghosting of one image over the other). Not having to put a new cable in though often makes this a good option, but something to be aware of. If your monitor only powers one camera at a time then this wouldn't be a problem, however a lot of monitors power all the connected cameras whenever it is powered on.
These cables are for a standard 4 pin aviation style connector. There are several variations of 4 pin connector so please check these will fit.
PLEASE NOTE: If you wish to split a video with one signal going to a monitor and the other going to a recorder then this cable will not do that. We do stock a 4 pin Y-splitter cable that will do the job though. Please contact us for details.